Headband adjustment mechanism for a headband



FIG. 1 is a perspective view showing the new design for a headband adjustment mechanism for a headband;

FIG. 2 is another perspective view thereof;

FIG. 3 is a back view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof;

FIG. 7 is a top view thereof; and,

FIG. 8 is a bottom view thereof. 

CLAIM The ornamental design for a headband adjustment mechanism for a headband, as shown and described. 